APL5912-KAC-TR Ver la hoja de datos (PDF) - Anpec Electronics
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APL5912-KAC-TR Datasheet PDF : 20 Pages
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APL5912
Functional Pin Description
GND (Pin 1)
Ground pin of the circuitry. All voltage levels are measured
with respect to this pin.
FB (Pin 2)
Connecting this pin to an external resistor divider
receives the feedback voltage of the regulator. The
output voltage set by the resistor divider is determined
by : VOUT = 0.8 ⋅ 1 + R1
(V)
R2
where R1 is connected from VOUT to FB with Kelvin
sensing and R2 is connected from FB to GND. A
bypass capacitor may be connected with R1in parallel
to improve load transient response. The recommended
R2 and R1 are in the range of 100~10kΩ.
VOUT (Pin 3,4)
for the main supply voltage. Please tie the Exposed
Pad and VIN Pin (Pin 8) together to reduce the dropout
voltage. The voltage at this pins is monitored for Power-
On Reset purpose.
VCNTL (Pin 6)
Power input pin of the control circuitry. Connecting
this pin to a +5V (recommended) supply voltage
provides the bias for the control circuitry. The voltage
at this pin is monitored for Power-On Reset purpose.
POK (Pin 7)
Power-OK signal output pin. This pin is an open-drain
output used to indicate status of output voltage by
sensing FB voltage. This pin is pulled low when the
rising FB voltage is not above the VPOK threshold or
the falling FB voltage is below the VPNOK threshold,
indicating the output is not OK.
Output of the regulator. Please connect Pin 3 and 4
together using wide tracks. It is necessary to connect
a output capacitor with this pin for closed-loop
compensation and improving transient responses.
VIN (Pin 5) and Exposed Pad
Main supply input pins for power conversions. The
Exposed Pad provide a very low impedance input path
EN (Pin 8)
Enable control pin. Pulling and holding this pin below
0.3V shuts down the output. When re-enabled, the IC
undergoes a new soft-start cycle . Left this pin open,
an internal current source 10µA pulls this pin up to
VCNTL voltage, enabling the regulator.
Functional Description
Power-On-Reset
Internal Soft-Start
A Power-On-Reset (POR) circuit monitors both input
voltages at VCNTL and VIN pins to prevent wrong logic
controls. The POR function initiates a soft-start
process after the two supply voltages exceed their
rising POR threshold voltages during powering on. The
POR function also pulls low the POK pin regardless
the output voltage when the VCNTL voltage falls be-
low it’s falling POR threshold.
An internal soft-start function controls rise rate of the
output voltage to limit the current surge at start-up.
The typical soft-start interval is about 2mS.
Output Voltage Regulation
An error amplifier working with a temperature-compensated
0.8V reference and an output NMOS regulates output
to the preset voltage. The error amplifier designed with
Copyright © ANPEC Electronics Corp.
11
Rev. A.6 - Jun., 2005
www.anpec.com.tw
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